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Over the past 2 weeks I have lost all of my Danios and now My cories keep turning up dead.I believe it could be some disease.My tetras and my pleco are doing just fine.The cories develop a white scaley looking thing on their face about a day before they die.Does anybody know what this could be? Should I take the other fish out and completley clean the tank? My water parimeters check out fine.What is going on???

I guess I should mention that the water parameters are at the bottom of the scale in ammonia and nitrite.I always have alittle ammonia in the tank every time I test it.I do water changes and everything.Nothing that should be in the danger stage.

Guppy_Man,

The white stuff on the face, is it fluffy like cotton (aka Mouth Fungus)?

I always have alittle ammonia in the tank every time I test it

Except if you have a really fancy test kit that detects tiny amounts of ammonia, any visible indicator (in particular if they happen on every test you perform) is a sign of ammonia in the water and as such bad for your fish, potentially even fatal.

Under good conditions, a test kit shows no readings at all for ammonia.

Ingo

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Proud Member of the New Jersey Aquatic Gardeners Club

No it is not like cotton,more like loose scales,but it's not scales.It is all over the head about 24 hours before death.2 of my glowlights also had it,1 on it's back and the other on it's eye,but it cleared up after a couple days.Also I just have a Aquarium pharmaceuticals ammonia test and a tetra test nitrite test,about $7 each.It would say there is alittle of both in bottled water so I don't know how good they are.

How big is the pleco. I have heard of plecos making snacks out of small fish, especially Cory's. If he is really big I recommend moving him to a different tank with larger fish.

I have a butterfly pleco that is about 6 inches long.He does bully the cories if they get too close to "His" algae tab.I have never actually seen him attack them though.I took the last 3 cories out and put them in a 5 gal.It does look like atleast one of them were attacked by something.I really don't think that any of them are going to make it.

could be many problems:
- wats ph sitting on.. sounds like it could be acid.. acidic ph burns scales of the fish and results in wat looks like white skin peeling off on the fish.. i'd check it out if you dont have a ph test kit ask ur local lfs to check it or purchase one.. they always come in handy.

- if you do have ammonia then u have a certain problem.. how long has the tank been setup for?? i would do a water change asap.. and see if you can get ur hands on a product called amtrite down.. dose weekly for 2 weeks and you will no longer have problems.

i dont think the pleco would be a problem.

r0b3y

my ph is 7.2.my tank is about 2 years old.I do bi-weekly water changes and I have never been able to get the ammonia level down to 0.No matter what I do or use.There is always a little.All my other fish are doing great.

If you are using Seachem Prime or a similar additive for your water changes, your test kit may show a trace of ammonia.

I would strongly consider shifting to a weekly water change regimen of at least 25%. During that water change you should thoroughly vacuum your substrate. Great maintenance minimizes fish loss. Corydoras can be touchy as they are very sensitive to a build-up of nitrates. Water changes reduce nitrates.

The following are possible diseases from http://www.corydorasworld.com/

Velvet (Oodinium)

Velvet is caused by a dinoflagellate, classified by some as an alga because it carries Chlorophyll.
There are two main species, Oodinium limmneticum and Oodinium pillularis.
The free swimming stage of Velvet settles on the skin and gills of the fish, adhering at first by its long flagellum, later putting out pseudopodia, (similar to fingers) that penetrate the skin and give it a very firm grip.
Velvet has a similar life cycle to White spot, feeding and becoming a cyst it produces upward of 200 young before dropping off.
The appearance is similar to gold or brown dust over the body and fins which at times may appear to move.
Symptoms are similar to White spot, glancing off rocks etc.
As Velvet is highly contagious it is important to eradicate this problem as soon as possible.
Treatment is aimed at the free swimming stage and there are good cures available from your local store.
Copper sulphate can be used at a concentration of 0.2 mg per litre or 0.2 ppm.
This should be repeated after 3 days to ensure eradication.

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Fungus (Saprolegnia or Achyla)

Fungi are in fact colourless plants, they are very diverse in in form and have not been studied that much in fish.
Saprolegnia and Achyla are genera of fungi that attack weakened and injured fish, usually settling on damaged skin or gills, they will also attack the eggs of fish.
The spores enter the aquarium from the air so there is no way to stop possible outbreaks.
Threads of fungus spread under the skin forming a web like
structure and eventually produce tufts of external hyphae that may be large enough to look like cotton wool.
These form spores that become free swimming and can then go on to infect other fish that are weak or injured.
It is important that you remove any fish you suspect immediately to a hospital tank for treatment.
Symptoms of fungus are a grey or whitish growth in the skin of the fish, often associated with visible damage.
Treatment can be with Malachite green in a separate tank for 30 seconds at a strength of 60 mg per litre, repeat treatments may be necessary.
The fungus is stained by the Malachite and usually drops off within a few hours.
Keep the fish under observation for 2 or 3 days as fungus can sometimes regrow.



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Mouth Fungus (Columnaris)

Although Columnaris resembles fungus it is in fact a Bacterium.
It is usually found just around the mouth area, rarely spreading.
The first signs are a thin white line around the lips, which then grows into white or grey short tufts that resemble fungus.
Early treatment is needed if you are going to save the fish's life, due to the toxins released and the fact that the fish can not feed.
The best and most effective cure is to use Anti-Biotic.
Penicillin is very effective at 10.000 units per litre, with a second dose after two days.

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researched from Steven Wright